关键词: electron-positron pair production, frequency chirp, laser polarization, Dirac-Heisenberg-Wigner formalism, strong-field QED, spectral compression, critical threshold

Abstract: We investigate electron-positron pair production in frequency-chirped, polarized laser fields using the Dirac-Heisenberg-Wigner formalism. A key theoretical finding is the polarization-dependent critical chirp threshold $b_{\rm c}(\delta)$, which marks the transition between tunneling-dominated and multiphoton pair production regimes: $b_{\rm c}$ doubles as polarization evolves from linear ($\delta=0$, $b_{\rm c}(0)=0.02 {\rm m}^2$) to circular ($\delta=1$, $b_{\rm c}(1)=0.04 {\rm m}^2$). Above this threshold, chirp induces spectral compression with the momentum distribution width scaling as $\Delta q \propto b^{-1/2}$, concentrating pairs into a smaller phase-space volume and enhancing production yields by up to three orders of magnitude, following the universal scaling law $n \propto (b\tau)^{3/2}$. Notably, non-monotonic polarization dependence is observed at intermediate chirp values, where linear polarization temporarily surpasses circular in yield before convergence at large $b$. These results establish chirp as a precise control parameter for optimizing EP pair production in nonperturbative quantum electrodynamics, advancing the theoretical framework for understanding quantum vacuum dynamics and providing a foundation for structured pulse engineering in strong-field quantum electrodynamics.

Key words: electron-positron pair production, frequency chirp, laser polarization, Dirac-Heisenberg-Wigner formalism, strong-field QED, spectral compression, critical threshold